Hi nagaraju60,

I have created sample by refering the below article.

Calling ASP.Net AJAX PageMethods using ScriptManager Example

Check this example. Now please take its reference and correct your code.

I have made use of the following table Customers with the schema as follows.

.

You can download the script from the below link.

Download SQL file

HTML

<asp:ScriptManager ID="ScriptManager1" runat="server" EnablePageMethods="true">
</asp:ScriptManager>
<div>
    <asp:GridView ID="GridView1" runat="server" AutoGenerateColumns="false">
        <Columns>
            <asp:BoundField DataField="CustomerId" HeaderText="Id" />
            <asp:BoundField DataField="Name" HeaderText="Name" />
            <asp:BoundField DataField="Country" HeaderText="Country" />
        </Columns>
    </asp:GridView>
    <br />
    <asp:Button Text="Save" runat="server" ID="btnSave" OnClick="Save" />
</div>
<script type="text/javascript">
    function SaveRecord() {
        var table = document.getElementById("GridView1");
        for (var i = 1; i < table.rows.length; i++) {
            var row = table.rows[i];
            PageMethods.SaveRow(row.cells[1].innerHTML, row.cells[2].innerHTML, function OnSuccess(response) { });
        }
    }
</script>

C#

protected void Page_Load(object sender, EventArgs e)
{
    if (!this.IsPostBack)
    {
        BindGridView();
    }
}

private void BindGridView()
{
    DataTable dt = new DataTable();
    dt.Columns.AddRange(new DataColumn[3] { new DataColumn("CustomerId", typeof(int)),
                    new DataColumn("Name", typeof(string)),
                    new DataColumn("Country",typeof(string)) });
    dt.Rows.Add(1, "Mudassar Khan", "India");
    dt.Rows.Add(2, "John Hammond", "United States");
    dt.Rows.Add(3, "Suzanne Mathews", "France");
    dt.Rows.Add(4, "Robert Schidner", "Russia");
    GridView1.DataSource = dt;
    GridView1.DataBind();
}

protected void Save(object sender, EventArgs e)
{
    ScriptManager.RegisterStartupScript(this, this.GetType(), "", "SaveRecord();", true);
}

[System.Web.Services.WebMethod]
public static void SaveRow(string name, string country)
{
    SqlConnection conn = new SqlConnection(ConfigurationManager.ConnectionStrings["constr"].ConnectionString);
    SqlCommand cmd = new SqlCommand("INSERT INTO Customers (Name,Country) VALUES (@Name,@Country)", conn);
    cmd.CommandType = CommandType.Text;
    cmd.Parameters.AddWithValue("@Name", name);
    cmd.Parameters.AddWithValue("@Country", country);
    conn.Open();
    cmd.ExecuteNonQuery();
}

VB.Net

Protected Sub Page_Load(sender As Object, e As EventArgs) Handles Me.Load
    If Not Me.IsPostBack Then
        BindGridView()
    End If
End Sub

Private Sub BindGridView()
    Dim dt As New DataTable()
    dt.Columns.AddRange(New DataColumn(2) {New DataColumn("CustomerId", GetType(Integer)), New DataColumn("Name", GetType(String)), New DataColumn("Country", GetType(String))})
    dt.Rows.Add(1, "Mudassar Khan", "India")
    dt.Rows.Add(2, "John Hammond", "United States")
    dt.Rows.Add(3, "Suzanne Mathews", "France")
    dt.Rows.Add(4, "Robert Schidner", "Russia")
    GridView1.DataSource = dt
    GridView1.DataBind()
End Sub

Protected Sub Save(sender As Object, e As EventArgs)
    ScriptManager.RegisterStartupScript(Me, Me.[GetType](), "", "SaveRecord();", True)
End Sub

<System.Web.Services.WebMethod()> _
Public Shared Sub SaveRow(name As String, country As String)
    Dim conn As New SqlConnection(ConfigurationManager.ConnectionStrings("constr").ConnectionString)
    Dim cmd As New SqlCommand("INSERT INTO Customers (Name,Country) VALUES (@Name,@Country)", conn)
    cmd.CommandType = CommandType.Text
    cmd.Parameters.AddWithValue("@Name", name)
    cmd.Parameters.AddWithValue("@Country", country)
    conn.Open()
    cmd.ExecuteNonQuery()
End Sub

Output after inserting record to database.